Antiskid mechanism

ABSTRACT

An antiskid device is provided with a control valve actuated in response to signals from a sensing mechanism of impending vehicle skid conditions to respectively subject a control member to atmosphere and selectively subject said control member to vacuum for controlling the application of supplied fluid pressure to the vehicle brakes, and a resiliently urged member is provided for disabling said control member in the event the vacuum is lost.

' United States Patent Inventor 63141 Appl. No. 64,195

Filed Patented CEttlIW/l 17} 2,10 M Division of Ser. NM2J17 Max 8, 1969John A. Machek 11803 Spruce Haven, Creve Coeur, M0.

[56] References Cited UNITED STATES PATENTS 3,108,615 10/1963 Cripe137/625.66 3,542,289 11/1970 Ojala et al l37/625.66 X

Primary Examiner-Milton Buchler Assistant Examiner-John J. McLaughlinAltomey.loseph E. Papin ABSTRACT: An antiskid device is provided with acontrol valve actuated in response to signals from a sensing mechanismof impending vehicle skid conditions to respec- ANTISKID MECHANISMllClaims,2DrawingFigs.

US. Cl 137162565, 251/282 lnt.Cl E03b-l/ 02 FieldofSearch.... 251/282;137/625.2, 625.65, 625.66

33 67 68 42 A 4 57 \A \A 65 47 59 6L r r so 2' 62 52 gll 4s; 70 53AN'IISKID MECHANISM This application is a division of copendingapplication Ser. No. 823,087 filed May 8, 1969.

This invention relates in general to brake systems and in particular toantiskid devices for use therein.

In the past, antiskid devices were provided with a control member forcontrolling the application of supplied fluid pressure to vehiclebrakes. The control member was movable from a position establishing openpressure fluid communication between fluid pressure generating means,such as a master cylinder, and a fluid pressure responsive motor, suchas a wheel cylinder of a wheel brake, toward an isolating positioninterrupting pressure fluid communication between said master cylinderand wheel cylinder when the applied fluid pressure acting thereonexceeded a predetermined value. The control member defined an expansiblefluid pressure chamber in the antiskid device which was subjected to theapplied fluid pressure when said control member was in its isolatingposition, and said control member was movable to expand said chamberthereby increasing the volume thereof to reduce the magnitude of theapplied fluid pressure at the wheel cylinder in response to signalssupplied to said antiskid device from a sensing mechanism upon theoccurrence of impending vehicle skid conditions. The movement of thecontrol member toward its isolating position and chamber expansionposition was opposed by a spring having a rather intense compressiveforce, and a power piston was provided to selectively control the forceof the spring exerted on the control member. In some antiskid device,the power piston was either vacuum or air suspended wherein therespective introduction of atmospheric air or vacuum on one side thereofestablished a differential force across said power piston which wasutilized to oppose the spring force, and in this manner with the springforce so contained or disabled, the applied fluid pressure acting onsaid control member was effective to urge said control member toward itsisolating and chamber expanding positions. One of the disadvantages orundesirable features of such past antiskid devices was that the springwhich opposed movement of the control member created a delay or responsetime in the reaction of the control member. In other words, after theantiskid device had received the signal from the sensing mechanism of animpending vehicle skid condition, it was necessary to then establish thedifferential force by selectively subjecting the power piston to thedifferential air-vacuum pressure having a magnitude great enough toovercome the force of the spring before the control movement of thecontrol member could be effected. In addition, this undesirable delay,of course, created an undesirable null spot or range in the operatingcharacteristics of the control member.

In addition, the past antiskid devices were provided with a controlvalve which selectively subjected one side of an atmospheric suspendedpower piston to the vacuum source to establish the driving force formoving the control member, and the movement of such control valve toselectively subject the power piston to vacuum was effected by asolenoid in response to signals received from a sensing mechanism whichascertained impending vehicle skid conditions. Another disadvantageousor undesirable feature of such past antiskid devices is that the controlvalves thereof were responsive to the differential fluid pressure of theatmosphere and vacuum acting thereacross to establish forces whichopposed or hindered actuation by the solenoid.

The primary object of the present invention is to provide an antiskiddevice which overcomes the aforementioned disadvantageous or undesirablefeatures, as well as others, and this, along with other advantageous anddesirable features of the present invention, will become apparent in thespecification which follows.

Briefly, the present invention includes an antiskid device for drivingsaid control means toward a position effecting open pressure fluidcommunication between the supplied and applied fluid pressures in theevent the vacuum is lost. Another aspect of the present inventionincludes a control valve actuated by a solenoid for controlling theselective subjection of the control means to the differential air-vacuumpressure, said control valve having substantially equal and opposedeffective areas respectively subjected to the differential air-vacuumpressure.

In the drawing, which illustrates an embodiment of the invention andwherein like numerals refer to like parts wherever they occur:

FIG. 1 is a sectional view illustrating a preferred embodiment of thepresent invention in cross section, and

FIG. 2 is a partial sectional view taken along line 2-2 of FIG. 1.

Referring now to the drawings in detail and in particular to FIG. 1, anantiskid device 1 is provided with power and control housings 2, 3interconnected against displacement by a plurality of studs 4.

The power housing 2 is provided with a pair of opposed, cup-shapedcylinder or housing member 5,6 having opposed peripheral edges 7, 8releasably secured against displacement by a conventional clamping band9, and a pair of split or separate disabling and control diaphragmmembers 10, 11 are compressed in sealing engagement between said opposededges dividing said power housing into separate chambers l2, l3 and 14,respectively, which are isolated from each other. The base portions 15,16 of the housing members 5, 6 are respectively provided with axiallyaligned apertures l7, l8 therethrough, and the diaphragm 10 is alsoprovided with a centrally located sealing aperture 19 therethroughsubstantially aligned with said base portion aperture 17.

A venting piston 20 having an annular flange 21 on the leftward orinterior end thereof extends through the diaphragm aperture 19, and thediaphragm 10 is positioned in sealing engagement between said pistonflange and a diaphragm retainer 22 carried in said piston by suitablemeans, such as the snap ring and groove assembly 23 provided in theperipheral portion of said piston. The piston 20 extends coaxiallythrough the chamber 12 and is slidably received in a bore 24 axiallyprovided through a hub or extension 25 which extends through the housingmember aperture 17 into said chamber, said hub being sealably connectedwith the housing member base 15 about said aperture by suitable means,such as a weld 26. The piston'20 is also provided with a peripheral seal27 in sealing engagement with the hub bore 24, and a bore 28 is axiallyprovided through said piston venting' the chamber 13 to the atmosphereat all times.

A port 29 is provided in the housing member 5 in communication with thechamber 12 for connecting said chamber with a vacuum source, asdiscussed hereinafter, and a plurality of disabling springs 30 aredisposed in said chamber having their additive compressive forces Fccontained between the diaphragm retainer plate 22 and the housing memberbase wall 15, said base wall having a plurality of indentations orscalloped portions 31 defining both seats for positioning engagementwith said disabling springs and stops for engagement with said diaphragmretainer plate.

The control housing 3 is provided with a bore 32 interposed betweenopposed counterbores 33, 34 which are aligned with the apertures 18provided in the housing member base wall 16, and a shoulder 35 defininga valve seat is provided on said housing at the juncture of the bore 32and counterbore 34. The counterbore 34 defines an inlet port which isthreaded to receive an inlet fitting 36 for connection in pressure fluidcommunication with fluid pressure generating means, such as a mastercylinder (not shown), and a valve spring 37 is biased between saidfitting and a check or ball-type valve member 38 urging said valvemember toward seating engagement with the valve seat 35. An outlet port39 which is connected in pressure fluid communication with a fluidpressure responsive motor or wheel cylinder of a vehicle brake (notshown) is also provided in the housing 3 intersecting with thecounterbore 33 adjacent to the leftward end thereof, and an annular seal40 is seated in 1 a recess 41 provided in the rightward end of saidcounterbore. A control piston or member 42 is slidably received in thecounterbore 33 disposed in sealing engagement with the seal 40, and aneffective area A is provided in the leftward end of said control pistonwhich defines with said counterbore an expansible fluid pressure chamber43 in open pressure fluid communication with the outlet port 39 at alltimes. Another extension 44 is integrally formed on the leftward end ofthe control piston 42 and extends coaxially through the housing bore 32having a free end in the counterbore 34 normally engaged with the valve38 to maintain said valve displaced from its housing seat 35. Therightward end of the control piston extends through the aperture 18 inthe base wall 16 of the housing 6 into the chamber 14, and a diaphragmretainer plate 45 and stop member connected with said control pistonrightward end for abutting engagement with the diaphragm l l and thehousing base wall 16, respectively.

Referring now also to FIG. 2, the control housing 3 is also providedwith a cross-bore 47 interposed between a crosscounterbore 48 andstepped cross-counterbores 49, 50, and shoulders 51, 52 and 53 areprovided on said control housing at the juncture of said cross-bore withthe cross-counterbores 48, 49, and between the steppedcross-counterbores 49, 50, respectively, said opposed shoulders 51, 52defining valve seats. Another bore or connecting passage 54 is providedin the control housing 3 having one end intersecting with the cross-bore47 adjacent to its midportion and the other end thereof connected inopen pressure fluid communication with the power housing chamber 14through another aperture 540 provided in the base wall 16 of the powerhousing member 6. Atmospheric and vacuum ports 55, 56 for connectionwith the atmosphere and the vehicle vacuum source are provided in thecontrol housing intersecting with the cross-counterbores 48, 49,respectively, and another vacuum or connecting port 57 is also providedin said control housing intersecting with the cross-counterbore 49, saidconnecting port 57 and the port 29 in the power housing member beinginterconnected by a conduit or hose 58 to subject the power housingchamber 12 to the available vacuum at the vacuum port 56 at all times.

A dumbbell-type control valve, indicated generally at 59, is providedwith a stem portion 60 which extends coaxially through the cross-bore 47having spaced opposed valve member 61, 62 thereon in thecross-counterbores 48, 49 for sealing engagement with the valve seats51, 52, said sealing engagement between said valve members and seatsdefining effective areas A A;,, as discussed hereinafter. The rightwardend of the valve stem 60 is connected with an armature 63 of anelectrical solenoid 64 of a type well known in the art which is threadedinto the open end of the cross-counterbore 48, and a return spring 65 ofa relatively small compressive force Fs normally urges the control valve59 toward its nonnal position engaging the valve member 61 with itsvalve seat 51 and displacing the valve member 62 from its valve seat 52.

A valve balancing assembiy, indicated generally at 66, is provided witha valve diaphragm 67 in abutting engagement with an abutment plate orwasher 68 having a centrally located aperture 69 therethrough, and saidabutment plate is positioned in engagement with the housing shoulder 53by a snap ring and groove assembly 70 provided in the leftward end ofthe cross-counterbore 50 in displacement preventing engagement with thevalve diaphragm 67. The working portion of the diaphragm 67 defines aneffective area A, having the exterior side thereof subjected to theatmosphere and the interior side exposed to the available vacuum at thevacuum port 56 through the abutment plate aperture 69, and it should benoted that the effective areas A,, A and A are substantially equal. Aconnecting or driving member 71 is movable through the abutment plateaperture 69 having an annular flange 72 on its leftward end engaged withthe valve diaphragm 70 and movable toward motion limiting engagementwith the abutment plate 68 and an abutment 73 on its rightward enddefining a lost motion connection with the valve stem 60 and normallyengaged therewith. To complete the description of the device 1, thedriving member 71 is provided with an axial guide bore 74 in therightward or free end thereof in which is slidably received a reducedextension 75 provided on the leftward end of the valve stem 61.

In the operation and assuming, of course, that the vehicle is operativeto establish vacuum at the vacuum port 56, the component parts of theantiskid device 1 are in their normal operating positions, as shown inthe drawings and as described hereinbefore; therefore, the power housingchamber 12 is evacuated through the power housing member port 29, thehose 58, the control housing connecting port 57 and crosscounterbore 49to said vacuum port, and the power housing chamber 14 is evacuatedthrough the control housing connecting passage 54, the bore 47, and saidcross-counterbore to said vacuum port. Since the power housing chamber13 is subjected 'to the atmosphere at all times through the ventingpiston bore 28, as previously mentioned, the evacuation of the chambers12, 14 establishes a control differential fluid pres sure acting acrossthe diaphragms 10, 11 to create opposed differential forces F Frespectively. The F, urges the diaphragm l0 rightwardly in the powerhousing 2 against the additive compressive forces Fc of the disablingsprings 30 toward an inoperative position engaging the diaphragm plate22 with the indentations 31 of the power housing member 5. The force Furges the diaphragm ll leftwardly in the power housing 2 to engage thestop 46 with the base wall 16 of the power housing member 6 and urgesthe control piston leftwardly in the counterbore 33 of the controlhousing 3 to engage the control piston extension 44 with the check valve38 and maintain said check valve disengaged from its seat 35 therebyestablishing open pressure fluid communication between the inlet andoutlet ports 34, 39. In this manner, supplied fluid pressure from themaster cylinder (not shown) flows from the inlet port and fitting 34, 36through the control housing bore and chamber 32, 43 to the outlet port39 being applied therefrom to energize a vehicle brake wheel cylinder(not shown) and the applied fluid pressure at said outlet port acts onthe effective area A of the control piston 42 to establish a force F inopposition to the force F, acting on the control piston 44.

When the brake wheel cylinder is so energized, the rate of the vehiclevelocity is, of course, decreased, and a sensing device (not shown) isutilized to measure decreasing rate of velocity and ascertain thecritical rate thereof denoting impending vehicle skid conditions, suchas in the event the applied fluid pressure is great enough to lock upthe vehicle brake. When the sensing device ascertains such impendingvehicle skid condition, it signals the solenoid 64 which is thenelectrically energized to move the control valve 59 rightwardly againstthe compressive force F: of the return spring 65 toward an operativeposition engaging the valve member 62 with its valve seat 52 anddisengaging the valve member 61 from its valve seat 51. Of course, theengagement of the valve member 62 with the valve seat 52 isolates thepower housing chamber 14 from the vacuum port 56, and the disengagementof the valve member 61 from the valve seat 51 effects the flow ofatmospheric air from the atmospheric port 55 through the cross-bore andcounterbore 47, 48 and the connecting passage 54 into the power housingchamber 14 thereby eliminating the control differential fluid pressureacting across the diaphragm 11 as well as the force F,. Upon theelimination of the force F the opposing force F, of the applied fluidpressure at the outlet port 39 acting on the effective areas A, of thecontrol piston 42 moves said control piston and diaphragm 11 rightwardlywhich expands and increases the volume of the chamber 43; therefore,since the check valve 38 is closed interrupting pressure fluidcommunication between the inlet and outlet ports 34, 39, the volumetricexpansion of the chamber 43 reduces the magnitude of the applied fluidpressure at said outlet portion which, of course, serves to reduce theintensity of the vehicle brake and actuation and the vehicledeceleration rate thereby obviating the impending vehicle skidcondition. This increase in the rate of vehicle velocity is, of course,sensed by the sensing means which ascertains that the danger of avehicle skid condition is now past, and it again signal the solenoid 64which is then deenergized. Upon deenergization of the solenoid 64, thecompressive force Fs of the valve return spring 65 urges the controlvalve 59 leftwardly toward its normal position reengaging the valvemember 61 with its valve seat 51 and again disengaging the valve member62 from its valve seat 52 to selectively interrupt pressure fluidcommunication between the atmospheric port 55 and the power housingchamber 14 and selectively reestablish communication between said powerhousing chamber 14 and the vacuum port 56. In this manner, the powerhousing chamber 14 is again evacuated to reestablish the controldifferential fluid pressure acting across the diaphragm 11 and the forceF and the reestablished force F overcomes the opposing force F to movethe control piston 44 leftwardly toward its original position therebyreducing the volume of the chamber 43 and reestablishing the magnitudeof the applied fluid pressure at the output port 39. When the magnitudeof the applied fluid pressure at the outlet port 39 is so reestablished,the intensity of the brake energization is increased and the vehiclevelocity rate decreased to again cause the sensing device to signal forthe energization of the solenoid 64.

From the foregoing, it is obvious that the operating cycle of theantiskid device 1 is repetitive to continually alleviate impendingvehicle skid conditions until the master cylinder is deactuated toeliminate the supplied fluid pressure at the inlet port 34 wherein theapplied fluid pressure at the outlet port 39 acts on the effective areaof the check valve 38 to displace its from its seat 35 against the valvespring 37 establishing a return flow of applied fluid pressure to reducethe magnitude thereof which also reduces the magnitude of the force FUpon the reduction of the force F, the force F will return the diaphragmand control piston 42 leftwardly toward its communicating positionurging the check valve 38 against its spring 37 and from its seat 35 toreestablish open pressure fluid communication between the inlet andoutlet ports 34, 39 for the return flow of displaced fluid pressure.

in the event of the loss of the vehicle vacuum source wherein the vacuumnormally available at the vacuum port 56 is replaced by atmosphericpressure, such atmosphere flows through said vacuum port 56, the controlhousing cross-bore and cross-counterbore 47, 49 and the connectingpassage 54 into the power housing chamber 14 eliminating the controldifferential fluid pressure acting across the diaphragm l0 and the forceF The atmosphere also flows from the control housing cross-counterbore49 through'the connecting port 57, the hose 58 and the power housingport 29 into the chamber 12 eliminating the control differential fluidpressure acting across the diaphragm l0 and the disabling force F Uponthe elimination of the force F, the compressive forces Fc of thedisabling springs 30 urge the diaphragm l0 and plate 22 leftwardly intodriving engagement with the diaphragm 11 to concertedly drive saiddiaphragm 11 and control piston 42 toward their original orcommunicating positions maintaining the check valve 38 displaced fromits seat 35 and establishing open pressure fluid communication betweenthe inlet and outlet ports 34, 39. From the foregoing, it is obviousthat upon the loss of vehicle vacuum, the disabling springs 30 areeffective to drivingly engage the diaphragms 10, 11 and disable thecontrol piston 42 in order to provide open pressure fluid communicationbetween the inlet and outlet ports 34, 39 for the application of thesupplied fluid pressure therethrough to actuate the vehicle brakeswithout the aforementioned regulating or altering effect of the controldiaphragm and piston 11, 42 on the applied fluid pressure in response toimpending skid conditions of the vehicle.

Referring now in detail to the operation of the control valve 59, withthe control differential fluid pressure of the atmosphere and vacuum atthe ports acting across the valve member 61 on the area A; a force F 4is created additive to the compressive force Fs of the return spring 65urging the control valve 59 toward its normal position, as shown in FIG.2, and urging the valve member 61 toward engagement with its seat 51.The vacuum at the port 56 and the atmosphere also acts across the valvediaphragm 67 on the area A. thereof to create another force F,, inopposition to the force F urging said valve diaphragm and the drivingmember 71 rightwardly toward engagement with the control valve 59. Sincethe areas A A are substantially equal and the differential fluidpressures acting thereacross are also substantially equal, the forces F4 F are self-cancelling when the valve member 59 is in its normaloperating position; therefore, when the solenoid 64 is actuated, it isinitially opposed only by the relatively small compressive force of thereturn spring 65. The magnetic or operating characteristics ofsolenoids, such as the solenoid 64, require an extremely high excitingcurrent to energize the armature 63 and effect the initial actuationthereof, as compared for instance with the current necessary to maintainsaid armature in its energized position in magnetic holding engagementwith the pole piece (not shown) of said solenoid. In other words, oncethe armature 63 is magnetically urged toward or engaged with thesolenoid pole piece, the current necessary to maintain said magneticholding engagement is appreciably less than that needed to excite orinitiate the movement of said armature toward said pole piece, and thischaracteristic is, in the most part, due to the air gap between saidarmature and pole piece. Therefore, since the exciting current isextremely high, it is desirable to balance the forces F F acting on thecontrol valve 59 so that the exciting current acting on the armature 63to effect the initial actuation thereof is opposed only by the rathersmall force of the return spring 65. Of course, with the forces F F sobalanced, it is apparent that smaller electrical coils (not shown) canbe employed in the solenoid 64 to actuate the armature 63 and thecontrol valve 59 since the forces opposing the solenoid exciting currentare predeterminately minimized.

When the solenoid 64 receives its energization signal from the sensingdevice, as discussed hereinbefore, the armature is moved rightwardlytoward magnetic holding engagement with its pole piece against only theforce Fs of the return spring 65 and is accompanied by the rightwardmovement of the control valve 59 toward its operating position todisengage the valve member 61 from its seat 51 and move the valve member62 into engagement with its seat 52. With the control valve 59 in itsoperating position, the control housing bore and connecting passage 47,54 are isolated from the vacuum port 56 and communicated with theatmospheric port 55, as previously discussed, As previously mentioned,the stroke of the valve member 62 from its normal position disengagedfrom its seat 52 toward its operating position engaged with its seat isgreater than the stroke of the driving piston flange 72 into engagementwith the stop plate 68; therefore during the initial movement of thecontrol valve 59 toward its operating position, the driving member 71 isdrivingly engaged with said control valve with the force F actingthereon, but when the driving piston flange 72 is moved into abutmentwith said stop plate the force F is transferred to the control housing3. As previously noted, once the armature 63 is excited and movingtoward its pole piece, the current necessary to maintain such movementtoward magnetic holding engagement with said pole piece is relativelysmall as compared with the exciting current; therefore, the force F, isinitially utilized to assist the movement of the control valve 59 towardits operative position in response to the energization of the solenoidarmature 63.

When the control valve 59 is in its operative position and disengagedfrom the driving piston 71, the force F, is contained by the housing 3,and the valve member 61 is disengaged from its seat 51 subjecting thearea A, to the atmosphere thereby eliminating the force F Since thevalve member 62 is engaged with its seat 52 in the operative position ofthe control valve 59, the control differential fluid pressures of theatmosphere and vacuum at the ports 55, 56 acting across said valvemember on the areas A establishes another force F additive to the forceFs of the return spring 65 and urging said control valve leftwardlytoward its original position against the magnetic holding force orattraction between the armature 63 and the pole piece of the solenoid64. When the solenoid 64 receives its deenergization signal from thesensing means, as previously mentioned, the holding force between thearmature 63 and the pole piece of said solenoid is eliminated, and theforce F; of the return spring 65 assisted by the force F initiates thereturn leftward movement of the control valve 59 toward its originalposition. The initial return movement of the control valve 59 disengagesthe valve member 62 from its seat 52 and thereafter engages the drivingpiston 71 having the opposing or rightwardly directed force F thereon;however, at this time, both valve members 61, 62 are unseated so thatmomentarily the cross-counterbore 49 is subjected to a pressureapproaching atmosphere. In this manner, the force F is substantiallyeliminated when the pressure in the cross-counterbore 49 approachesatmosphere, and the return spring force Fs is then unopposed tothereafter concertedly drive the control valve 59 and driving piston 71leftwardly toward their normal positions. Once the valve member 61 isreengaged with its seat 51 in the normal position of the control valve59, the cross-counterbore 49. is again isolated from the atmosphere andsubjected only to the vacuum at the port 56; therefore, the force F. isreestablished along with the opposing force F 5 From the foregoing, itis now apparent that a novel antiskid device 1 meeting the objects andadvantageous features set forth hereinbefore, as well as others, isprovided and that changes as to the precise configurations, shapes anddetails of the construction set forth in the disclosure by way ofillustration may be made by those skilled in the art without departingfrom the spirit of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A control valve comprising a housing having atmospheric, vacuum anddelivery ports therein, valve means movable in said housing between oneposition isolating said atmospheric port and connecting said vacuum anddelivery ports in pressure fluid communication and another positionisolating said vacuum port and connecting said atmospheric and deliveryports in pressure fluid communication, the atmosphere and vacuum at saidatmospheric and vacuum ports acting on said valve means to establish aforce urging said valve means toward its one position when said valvemeans is in its one position and said force being eliminated uponmovement of said valve means toward its other position, other means forsubjection to the vacuum at said vacuum port and the atmosphere anddrivingly engaged with said valve means in its one position, the vacuumat said vacuum port and the atmosphere acting on said other means toestablish another force substantially equal and opposite to the firstnamed force and urging said other means to driving engagement with saidvalve means in its one position, and abutment means on said housing forengagement with said other means, the other force urging said othermeans into engagement with said abutment means upon the movement of saidvalve means toward its other position.

2. A control valve according to claim 1, wherein said other meansincludes diaphragm means disposed in said housing and having opposedsides respectively subjected to the atmosphere and to the vacuum at saidvacuum port, and a driving connection between said diaphragm means andsaid valve means in its one position for engagement with said abutmentmeans.

3. A control valve according to claim 2, wherein said driving connectioncomprises piston means having opposed portions thereon, one of saidopposed portions being engaged with said valve means in its one positionand the other of said portions being engaged with said diaphragm means.

4. A control valve according to claim 3, comprising aperture means insaid abutment means, said piston means extending through said aperturemeans.

5. A control valve according to claim 4, wherein said other portionincludes flange means on said piston means engaged with said diaphragmmeans and movable into engagement with said abutment means about saidaperture means.

6. A control valve according to claim 1, comprising an effective area onsaid valve means for subjection to the atmosphere and vacuum at saidatmospheric and vacuum ports in the one position of said valve means andfor subjection to only the atmosphere at said atmospheric port in theother position of said valve means, said area being responsive to theatmosphere and vacuum at said atmospheric and vacuum ports respectivelyacting thereon to establish the first named force.

7. A control valve according to claim 1, comprising an effective area onsaid diaphragm means for subjection to the atmosphere and to the vacuumat said vacuum port, said area being responsive to the atmosphere andthe vacuum at said vacuum port acting thereon to establish the otherforce.

8. A control valve according to claim 1, comprising an effective area onsaid valve means respectively subjected to the atmosphere and vacuum atsaid atmospheric and vacuum ports to establish the first named force inthe one position of said valve means and being subjected to only theatmosphere at said atmospheric port to eliminate the first named forcein the other position of said valve means, and another effective area onsaid other means substantially equal to said first named area andsubjected to the vacuum at said vacuum port and to the atmosphere toestablish said other force.

9. A control valve according to claim 1, a valve seat on said housingbetween said atmospheric and delivery ports, said valve means includinga valve member engaged with said valve seat in the one position of saidvalve means, the sealing engagement of said valve member and said valveseat defining said first named area, said other means includingdiaphragm means sealably engaged with said housing between said vacuumport and the atmosphere, said other effective area being on saiddiaphragm means, and force transmitting means connected between saiddiaphragm means and said valve means in its one position and movableinto engagement with said abutment means upon the movement of said valvemeans to the other position.

10. A control valve according to claim 9, wherein said forcetransmitting means includes a piston having a free end portion engagedwith said valve means in its one position, and flange means on saidpiston having opposed abutments, one of said opposed abutments beingengaged with said diaphragm means and the other of said opposedabutments being predeterminately spaced from said abutment means forengagement therewith, said diaphragm means being movable in response tothe other force to drive said piston and engage said other opposedabutment with said abutment means upon the movement of said valve meanstoward its other position.

11. A control valve comprising a housing having a bore thereininterposed between a pair of opposed counterbores, a control port insaid housing intersecting said bore for connection with a motor, anatmospheric port in said housing intersecting with one of saidcounterbores and connected with the atmosphere, a vacuum port in saidhousing intersecting with the other of said counterbores for connectionwith a vacuum source, a pair of opposed valve seats on said housing atthe juncture of said bore with said counterbores, respectively, valvemeans movable in said housing including a pair of valve members in saidcounterbores for engagement with said valve seats, respectively, saidvalve means being movable between one position engaging one of saidvalve members with one of said valve seats to interrupt pressure fluidcommunication between said atmospheric and control ports and disengagingthe other of said valve members from the other of said valve seats toestablish pressure fluid communication between said vacuum and controlports and another position engaging said other valve members with saidother valve seat to interrupt pressure fluid communication between saidvacuum and control ports and disengaging said one valve member from saidone valve seat to establish pressure fluid communication between saidatmospheric and control ports, resilient means normally urging saidvalve means toward its one position, a first effective area on said onevalve member subjected to the vacuum and atmosphere at said vacuum andatmospheric ports to establish a first differential force urging saidvalve means in one direction when said valve means is in its oneposition and subjected to only the atmosphere at said at-, mosphericport to eliminate said first differential force upon movement of saidvalve means toward its other position, abutment means connected withsaid housing adjacent to the open end of said other counterbore,aperture means in said abutment means, diaphragm means closing the openend of said other counterbores, piston means extending through saidaperture means including a head portion engaged with said diaphragmmeans, an abutment on said head portion for engagement with saidabutment means, and another abutment J0 for engagement with said valvemeans in its one position, a second effective area on said diaphragmmeans substantially equal to said first area and subjected to theatmosphere and the vacuum at said vacuum port to establish a seconddifferential force substantially equal and opposite to the firstdifferential force to urge said diaphragm means into engagement withsaid piston means head portion and said other abutment into engagementwith said valve means in its one position, said diaphragm means andpiston means being concertedly movable in response to said seconddifferential force to engage said first named abutment with saidabutment means upon the initial movement of said valve means againstsaid resilient means toward its other position and said valve meansbeing thereafter disengaged from said other abutment upon furthermovement thereof toward the other position.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,613,733 Issued October 19, 1971 John A. Machek It is certified thaterror appears in the aboveidentified patent and that said Letters Patentare hereby corrected as shown below:

Column 1, line 31, "device" should read devices Column 2, line 64,"apertures" should read a erture Column 3, line 17, after "member"insert 46 are line 70, after "A delete the comma Column 4, line 22,after "The" nsert force line 68, "areas" should be area" line 74,"portion" should read port line 75, after "brake" delete and Column 5,line 33, "its" should read it line 55, after "F insert a comma Column 6,line 1, after "A insert a com line 9, after "A insert a com line 11,after "F insert a comma line 33, after "F insert a comma line 55, after"therefore" insert a comma Column 7, line 2, "areas" should read arealine 56, after "means insert in Signed and sealed this 6th day of March1973.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

1. A control valve comprising a housing having atmospheric, vacuum and delivery ports therein, valve means movable in said housing between one position isolating said atmospheric port and connecting said vacuum and delivery ports in pressure fluid communication and another position isolating said vacuum port and connecting said atmospheric and delivery ports in pressure fluid communication, the atmosphere and vacuum at said atmospheric and vacuum ports acting on said valve means to establish a force urging said valve means toward its one position when said valve means is in its one position and said force being eliminated upon movement of said valve means toward its other position, other means for subjection to the vacuum at said vacuum port and the atmosphere and drivingly engaged with said valve means in its one position, the vacuum at said vacuum port and the atmosphere acting on said other means to establish another force substantially equal and opposite to the first named force and urging said other means to driving engagement with said valve means in its one position, and abutment means on said housing for engagement with said other means, the other force urging said other means into engagement with said abutment means upon the movement of said valve means toward its other position.
 2. A control valve according to claim 1, wherein said other means includes diaphragm means disposed in said housing and having opposed sides respectively subjected to the atmosphere and to the vacuum at said vacuum port, and a driving connection between said diaphragm means and said valve means in its one position for engagement with said abutment means.
 3. A control valve according to claim 2, wherein said driving connection comprises piston means having opposed portions thereon, one of said opposed portions being engaged with said valve means in its one position and the other of said portions being engaged with said diaphragm means.
 4. A control valve according to claim 3, comprising aperture means in said abutment means, said piston means extending through said aperture means.
 5. A control valve according to claim 4, wherein said other portion includes flange means on said piston means engaged with said diaphragm means and movable into engagement with said abutment means about said aperture means.
 6. A control valve according to claim 1, comprising an effective area on said valve means for subjection to the atmosphere and vacuum at said atmospheric and vacuum ports in the one position of said valve means and for subjection to only the atmosphere at said atmospheric port in the other position of said valve means, said area being responsive to the atmosphere and vacuum at said atmospheric and vacuum ports respectively acting thereon to establish the first named force.
 7. A control valve according to claim 1, comprising an effective area on said diaphragm means for subjection to the atmosphere and to the vacuum at said vacuum port, said area being responsive to the atmosphere and the vacuum at said vacuum port acting thereon to establish the other force.
 8. A control valve according to claim 1, comprising an effective area on said valve means respectively subjected to the atmosphere and vacuum at said atmospheric and vacuum ports to establish the first named force in the one position of said valve means and being subjected to only the atmosphere at said atmospheric port to eliminate the first named force in the other position of said valve means, and another effective area on said other means substantially equal to said first named area and subjected to the vacuum at said vacuum port and to the atmosphere to establish said other force.
 9. A control valve according to claim 1, a valve seat on said housing between said atmospheric and delivery ports, said valve means including a valve member engaged with said valve seat in the one position of said valve means, the sealing engagement of said valve member and said valve seat defining said first named area, said other means including diaphragm means sealably engaged with said housing between said vacuum port and the atmosphere, said other effective area being on said diaphragm means, and force transmitting means connected between said diaphragm means and said valve means in its one position and movable into engagement with said abutment means upon the movement of said valve means to the other position.
 10. A control valve according to claim 9, wherein said force transmitting means includes a piston having a free end portion engaged with said valve means in its one position, and flange means on said piston having opposed abutments, one of said opposed abutments being engaged with said diaphragm means and the other of said opposed abutments being predeterminately spaced from said abutment means for engagement therewith, said diaphragm means being movable in response to the other force to drive said piston and engage said other opposed abutment with said abutment means upon the movement of said valve means toward its other position.
 11. A control valve comprising a housing having a bore therein interposed between a pair of opposed counterbores, a control port in said housing intersecting said bore for connection with a motor, an atmospheric port in said housing intersecting with one of said counterbores and connected with the atmosphere, a vacuum port in said housing intersecting with the other of said counterbores for connection with a vacuum source, a pair of opposed valve seats on said housing at the juncture of said bore with said counterbores, respectively, valve means movable in said housing including a pair of valve members in said counterbores for engagement with said valve seats, respectively, said valve means being movable between one position engaging one of said valve members with one of said valve seats to interrupt pressure fluid communication between said atmospheric and control ports and disengaging the other of said valve members from the other of said valve seats to establish pressure fluid communication between said vacuum and control ports and another position engaging said other valve members with said other valve seat to interrupt pressure fluid communication between said vacuum and control ports and disengaging said one valve member from said one valve seat to establish pressure fluid communication between said atmospheric and control ports, resilient means normally urging said valve means toward its one position, a first effective area on said one valve member subjected to the vacuum and atmosphere at said vacuum and atmospheric ports to establish a first differential force urging said valve means in one direction when said valve means is in its one position and subjected to only the atmosphere at said atmospheric port to eliminate said first differential force upoN movement of said valve means toward its other position, abutment means connected with said housing adjacent to the open end of said other counterbore, aperture means in said abutment means, diaphragm means closing the open end of said other counterbores, piston means extending through said aperture means including a head portion engaged with said diaphragm means, an abutment on said head portion for engagement with said abutment means, and another abutment for engagement with said valve means in its one position, a second effective area on said diaphragm means substantially equal to said first area and subjected to the atmosphere and the vacuum at said vacuum port to establish a second differential force substantially equal and opposite to the first differential force to urge said diaphragm means into engagement with said piston means head portion and said other abutment into engagement with said valve means in its one position, said diaphragm means and piston means being concertedly movable in response to said second differential force to engage said first named abutment with said abutment means upon the initial movement of said valve means against said resilient means toward its other position and said valve means being thereafter disengaged from said other abutment upon further movement thereof toward the other position. 